package vip.george.security.utils;

import org.apache.tomcat.util.codec.binary.Base64;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.SecureRandom;
import java.util.Random;

/**
 * @author gehaodong
 * @since 2024/3/20
 * <p>
 * AES加、解密算法工具类
 * </P>
 */
public class AesUtil {

    private static final Logger log = LoggerFactory.getLogger(AesUtil.class);

    /**
     * 加密算法AES
     */
    private static final String KEY_ALGORITHM = "AES";

    /**
     * key的长度，Wrong key size: must be equal to 128, 192 or 256
     * 传入时需要16、24、36
     */
    private static final Integer KEY_LENGTH = 16 * 8;

    /**
     * 算法名称/加密模式/数据填充方式
     * 默认：AES/ECB/PKCS5Padding
     */
    private static final String ALGORITHMS = "AES/ECB/PKCS5Padding";

    /**
     * 后端AES的key，由静态代码块赋值
     */
//    public static String key;
//
//    static {
//        key = getKey();
//    }

    /**
     * 随机生成一个AES的秘钥
     */
    public static String getKey() {
        StringBuilder uid = new StringBuilder();
        //产生16位的强随机数
        Random rd = new SecureRandom();
        for (int i = 0; i < KEY_LENGTH / 8; i++) {
            //产生0-2的3位随机数
            int type = rd.nextInt(3);
            switch (type) {
                case 0:
                    //0-9的随机数
                    uid.append(rd.nextInt(10));
                    break;
                case 1:
                    //ASCII在65-90之间为大写,获取大写随机
                    uid.append((char) (rd.nextInt(25) + 65));
                    break;
                case 2:
                    //ASCII在97-122之间为小写，获取小写随机
                    uid.append((char) (rd.nextInt(25) + 97));
                    break;
                default:
                    break;
            }
        }
        return uid.toString();
    }

    /**
     * 加密
     *
     * @param content    加密的字符串
     * @param encryptKey key值
     */
    public static String encrypt(String content, String encryptKey) {
        try {
            //设置Cipher对象
            Cipher cipher = Cipher.getInstance(ALGORITHMS);
            cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(encryptKey.getBytes(), KEY_ALGORITHM));

            //调用doFinal
            byte[] bytes = cipher.doFinal(content.getBytes(StandardCharsets.UTF_8));
            // 转base64
            return Base64.encodeBase64String(bytes);
        } catch (Exception e) {
            log.error("AES加密失败", e);
            throw new RuntimeException(e.getMessage());
        }
    }

    /**
     * 解密
     *
     * @param encryptStr 解密的字符串
     * @param decryptKey 解密的key值
     */
    public static String decrypt(String encryptStr, String decryptKey) {
        try {
            //base64格式的key字符串转byte
            byte[] decodeBase64 = Base64.decodeBase64(encryptStr);

            //设置Cipher对象
            Cipher cipher = Cipher.getInstance(ALGORITHMS);
            cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(decryptKey.getBytes(), KEY_ALGORITHM));

            //调用doFinal解密
            byte[] bytes = cipher.doFinal(decodeBase64);
            return new String(bytes);
        } catch (Exception e) {
            log.error("AES解密失败", e);
            throw new RuntimeException(e.getMessage());
        }
    }

    public static void main(String[] args) {
        String aesKey = "WTHC97O7D7u7467A";
        String s1 = encrypt("{\"name\": \"small jerry \",\"age\": 0}", aesKey);
        System.out.println(s1);
        System.out.println(decrypt("lVrGQdblNi3YkZZbkqEkOFjJX+ZImnAzr+Q0ZJb807kgwaMPzEbHIc+xnJTfaayWRHkTdYCKznTwoGQbj4VVpgD2vs6D6DPe8IWxEAJU22Y=", aesKey));
    }
}
